This patent application claims priority from a Japanese patent application No. 2000-043392 filed on Feb. 21, 2000, the contents of which are incorporated herein by reference.
1. Field of the Invention
This invention relates to a vehicle head lamp. More specifically, this invention relates to a vehicle head lamp in which movements of an element of the vehicle head lamp switch over light distribution patterns.
2. Description of the Related Art
A vehicle head lamp irradiates a low beam or a high beam such that a reflector reflects forwardly a light from a light source. Because different light distributions are required between the low beam and the high beam, two light sources provided with a light bulb or two light bulbs are commonly used. In these cases, the switching over the low beam and the high beam is achieved by alternating the turning on one light source (or bulb) and the other.
It is also commonly used that a vehicle head lamp in which the beam switching is carried out by use of a single light source. Such constitution may be required, especially in a two-beam vehicle head lamp which uses a discharge bulb serving as the light source bulb. In the vehicle head lamp having the single light source, it is necessary to switch over beams by moving an element of the vehicle head lamp.
By one of common ways, the beam switching is achieved by moving a movable shade. In this case, a shade driving unit 102 makes the movable shade 104 move to two predetermined positions where the shade 104 shades different amounts of light from the light source 106 to a reflective surface 108a of the reflector 108, as shown in FIG. 8.
The beam switching using the movable shade 104 requires a high beam sole region A(H) having a certain area in the reflective surface 108a of the reflector, that is a reflecting region outer the one dot chain line in FIG. 9. Accordingly, the reflective surface region A(L), namely the reflecting region inner the one dot chain line in FIG. 9, which is applied to the low beam must become small. Therefore, here is a problem that the light intensity of light in the low beam can be reduced.
This problem may occur not only in switching over the low and high beams by moving the movable shade but generally in changing the light distributions also by moving the movable shade.
Therefore, it is an object of the present invention to provide a vehicle head lamp, which is capable of overcoming the above drawbacks accompanying the related art.
It is further object of the present invention to provide a vehicle head lamp, in which the light distribution is changed by moving the element of the vehicle head lamp and the beam irradiations are obtained with sufficient intensities wherever the element is positioned.
The above and other objects can be achieved by combinations described in the independent claims. The dependent claims define further advantageous and exemplary combinations of the present invention.
According to the first aspect of the present invention, a vehicle head lamp for irradiating a light from a light source, the vehicle head lamp comprises: a main reflector for reflecting the light from the light source; a sub-reflector movable in a first position and a second position, wherein the sub-reflector forwardly reflects the light from the light source when the sub-reflector is in the first position, and the sub-reflector is inhibited from forwardly reflecting the light from the light source when the sub-reflector is in the second position; and a driving unit connecting to the sub-reflector to make the sub-reflector move between the first position and the second position.
According to the second aspect of the present invention, a vehicle head lamp attached to a vehicle which has a steering operation, the vehicle head lamp comprises: a right head lamp for irradiating a light from a light source including, a main reflector for reflecting the light; a sub-reflector movable in a first position and a second position, wherein the sub-reflector forwardly reflects the light from the light source when the sub-reflector is in the first position, and the sub-reflector is inhibited from forwardly reflecting the light from the light source when the sub-reflector is in the second position, and a driving unit connecting to the sub-reflector to make the sub-reflector move between the first position and the second position; and a left head lamp for irradiating a light from a light source including, a main reflector for reflecting the light, a sub-reflector movable in a first position and a second position, wherein the sub-reflector forwardly reflects the light from the light source when the sub-reflector is in the first position, and the sub-reflector is inhibited from forwardly reflecting the light from the light source when the sub-reflector is in the second position, and a driving unit connecting to the sub-reflector to make the sub-reflector move between the first position to the second position.
The summary of the invention does not necessarily describe all necessary features of the present invention. The present invention may also be a sub-combination of the features described above. The above and other features and advantages of the present invention will become more apparent from the following description of the embodiments taken in conjunction with the accompanying drawings.